Push-pull couplers are used to provide quick connection and release of various types of lines or hoses such as hydraulic fluid lines and pneumatic hoses. Typically the lines are pressurized. Generally a coupler is fixed to a base, a user connects the lines from a loading dock or other station through the coupler to a container on a vehicle and uploads or discharges the fluid. After the user has completed the delivery to the vehicle, the user may neglect to remove the lines. As the vehicle moves away from the station, the lines are pulled and a failure may occur, resulting in damage to the loading dock, the lines, the coupler and/or the vehicle. The direction of tensile force exerted by the line on the coupler to which it is connected may not be normal to the face of the coupler adapter, causing side loading, nonuniform stresses on the coupler and line and possible damage to either. Similar couplers could be used to connect and disconnect electrical power or signal conductors.
Further, it is often the case that such couplers are provided in pairs, such as couplers for a hydraulic supply line and a hydraulic return line. The couplers may be displaced from one another in such a way that a tensile force exerted by a first line on a first coupler may not be parallel to a tensile force exerted by a second line on a second coupler. In this situation, one or both of the adapter faces will not be normal to the tensile forces exerted by the lines and a tensile force along one line may be greater in magnitude than a tensile force exerted along the second line. The first line may be cleanly pulled out of the first adapter along a direction normal to its face, but the second line might be pulled out at angle to the second face, causing damage to the line or adapter. Damage to the hydraulic lines or adapters may cause fluid spillage and other hazards. There is thus a need to minimize the damage caused by inadvertent disconnection of fluid lines by physical displacement of a vehicle from a station.